The invention relates to a dialyser, in particular for haemodialysis, which comprises a housing with inflow and outflow pipes for blood and dialysis solution and open hollow filaments arranged in the housing and joined to one another at their ends, as well as to a dialyser cartridge, as well as a method for the manufacture of such a dialyser.
Haemodialysis requires a membrane of large surface area, some 1-1.5 m.sup.2 in size and 10-20 .mu.m thick, of a material capable of acting as a dialytic permeable membrane, for example, cellulose acetate, polyacrylonitrile and similar materials are capable to act as separating layer between the blood and the suitably composed dialysis solution. The membrane is relatively easily permeable for water and low molecular weight constituents of the blood, including also substances contained in urine. High molecular weight and corpuscular constituents are however almost completely retained.
Under the term dialysers for haemodialysis can be recognised spool or coil dialysers, plate dialysers and also capillary or hollow filament dialysers, in which the membrane is formed from a large number (e.g. 10,000) of hollow filaments having a diameter of about 150 .mu.m. In the hitherto usual arrangement the hollow filaments are collected into a loose bundle of parallel filaments and arranged in a cylindrical housing. The ends of the bundle of hollow filaments are sealed off and packed against the housing. The inflow and outflow of the blood stream is effected by connecting pieces screwed onto the ends of the housing. The dialysis solution flows, in countercurrent, along the outside of the capillaries or hollow filaments, inflow and outflow occurring via lateral connections in the vicinity of the ends of the housing.
In designing a hollow filament dialyser great efforts are made to achieve as great an effectiveness as possible, i.e. a flow distribution as uniform as possible is necessary in order to fully utilize the membrane surface. High flow velocities are also desirable since this reduces the diffusion resistance in the blood and dialysis solution. Furthermore, the blood filling volume should be as small as possible and the blood flow resistance should be low. A hollow filament dialyser in principle provides the necessary prerequisites in order to meet these requirements.